> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opaque.cash/llms.txt
> Use this file to discover all available pages before exploring further.

# Opaque Protocol

> Stealth payments, provable reputation, and cross-chain announcements in one TypeScript SDK.

Opaque is a cross-chain privacy stack for unlinkable payments and zero-knowledge reputation. Configure one client (`@opaquecash/opaque`) and integrate stealth sends, PSR attestations, inbox scanning, and Groth16 proofs without touching chain-specific libraries directly.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Install the SDK, derive keys, and run your first flow in five minutes.
  </Card>

  <Card title="OpaqueClient reference" icon="code" href="/sdk/opaque-client">
    Full API for the unified client: stealth, PSR, reputation, and UAB.
  </Card>

  <Card title="Create a schema" icon="layer-group" href="/guides/create-schema">
    Register a PSR schema and issue attestations on Ethereum or Solana.
  </Card>

  <Card title="Scan and sweep" icon="inbox" href="/guides/scan-and-sweep">
    Discover owned stealth outputs across chains and move funds to a fresh address.
  </Card>
</CardGroup>

## What you can build

| Capability                  | Description                                                                                  |
| --------------------------- | -------------------------------------------------------------------------------------------- |
| **Stealth payments (CSAP)** | EIP-5564 meta-addresses, one-time stealth destinations, on-chain announcements               |
| **Reputation (PSR)**        | Schema registry, stealth-bound attestations, Groth16 proofs without revealing identity       |
| **Cross-chain (UAB)**       | Relay announcements over Wormhole so payments on one chain appear in the other chain's inbox |

## Architecture at a glance

```mermaid theme={"dark"}
flowchart LR
  App["Your app"] --> Client["OpaqueClient"]
  Client --> EVM["Ethereum\nRegistry · Announcer · PSR"]
  Client --> SOL["Solana\nRegistry · Announcer · PSR"]
  Client --> WASM["cryptography.wasm\nscan · sweep · prove"]
  Client --> UAB["UAB / Wormhole\ncross-chain inbox"]
```

## Supported networks (testnet)

| Chain            | ID / cluster | Status                                    |
| ---------------- | ------------ | ----------------------------------------- |
| Ethereum Sepolia | `11155111`   | Stealth, PSR V2, UAB, reputation verifier |
| Solana devnet    | `devnet`     | Stealth, PSR V2, reputation verifier      |

Contract addresses ship inside the SDK (see [Deployments](/protocol/deployments)). Override any address via `OpaqueClient.create({ contracts: { ... } })`.

## Packages

Most apps only need **`@opaquecash/opaque`** (plus **`@opaquecash/react`** for React
apps). Contract addresses and program ids ship in the generated
**`@opaquecash/deployments`** registry. Lower-level packages (`stealth-chain`,
`psr-core`, `uab`, etc.) are re-exported when you need a narrow surface. See
[Installation](/sdk/installation).